The objective of this proposal is to further investigate the physiology of the isolated medial basal hypothalamus (MBH)-pituitary complex as it relates to luteinizing hormone (LH) release. To this end experiments are designed to determine the ability of the isolated MBH-pituitary axis to support LH release following electrochemical stimulation of luteinizing hormone-releasing hormone (LH-RH) activity in the MBH. Blood samples will be obtained before and after ECS and analyzed for LH as an index of LH-RH activity. In addition, blood samples for LH determination will also be obtained before and after complete hypothalamic deafferentation (CHD) from long term ovariectomized rats outfitted with chronic intravenous cannulas. Experiments are also proposed to directly determine the content of LH-RH in the MBH at several times after CHD and to examine whether estrogen priming will affect the LH-RH concentration. Another set of experiments are proposed to further investigate the effects of partial and complete hypothalamic deafferentation on the concentration of estrogen receptor assays and autoradiography. The last set of experiments make use of rats with deafferented MBH to study the effect of adrenergic and dopaminergic receptor modifying drugs on LH release as a model to study the role of catecholamines on LH release mechanisms in the MBH.